# US 8,542,878 B2 · Method of controlling a function of a device and system for detecting the presence of a living being > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,878 B2 - Document ID: US8542878B2 - Status: Granted - Kind: B2 - Application number: 13/254,863 - Filed: 2010-03-01 - Published: 2011-12-22 - Granted: 2013-09-24 - Earliest claimed: 2009-03-06 - Assignees: Koninklijke Philips N.V. - Applicants: Giovanni Cennini; Vincent Jeanne - Inventors: Giovanni Cennini; Vincent Jeanne - Web page: https://patentgrep.com/patent/US8542878B2 ## CPC - G06V 40/10: Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands - G06T 7/215: Motion-based segmentation - G06V 40/166: {using acquisition arrangements} - G06T 2207/20021: Dividing image into blocks, subimages or windows - G06T 2207/30076: Plethysmography - G06T 2207/30196: Human being; Person - G06T 2207/30242: Counting objects in image - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A method of controlling a function of a device, includes obtaining a sequence (19;34;48) of digital images taken at consecutive points in time. At least one measurement zone (25) including a plurality of image points is selected. For at least one measurement zone (25), a signal (30;41;55) representative of at least variations in a time-varying value of a combination of pixel values at at least a number of the image points is obtained and at least one characteristic of the signal (30;41;55) within at least a range of interest of its spectrum relative to comparison data is determined. The determination comprises at least one of: (i) determining whether the signal (30;41;55) has a spectrum with a local maximum at a frequency matching a comparison frequency to a certain accuracy; and (ii) determining whether at least a certain frequency component of the signal (30;41;55) is in phase with a comparison signal to a certain accuracy. The function is controlled in dependence on whether the determination is positive. ## Claims ### Claim 1 Method of controlling a function of a device, including: obtaining a sequence (19;34;48) of digital images taken at consecutive points in time using a camera; selecting at least one measurement zone (25) including a plurality of image points; for at least one measurement zone (25), obtaining a signal (30;41;55) representative of at least variations in a time-varying value of a combination of pixel values at at least a number of the image points, and determining at least one characteristic of the signal (30;41;55) within at least a range of interest of its spectrum relative to comparison data, the determination comprising at least one of: (i) determining whether the signal (30;41;55) has a spectrum with a local maximum at a frequency matching a comparison frequency to a certain accuracy; and (ii) determining whether at least a certain frequency component of the signal (30;41;55) is in phase with a comparison signal to a certain accuracy; and controlling the function in dependence on whether the determination is positive, wherein the method is unobtrusive to a living being present in a field of view of the camera, and wherein the living being can be in motion. ### Claim 2 (depends on 1) Method according to claim 1, wherein the sequence (19;34;48) of digital images is caused to be captured by the camera (2) upon completion of an initialization phase, the initialization phase including: measuring periodic intensity fluctuations in at least parts of images acquired by the camera (2) whilst camera settings are varied, and selecting values of the camera settings at which measured periodic intensity fluctuations in at least a range of frequencies are determined to be minimal. ### Claim 3 (depends on 1) Method according to claim 1, including determining a correction signal corresponding to a time-varying value of a combination of pixel values at at least a number of image points in an image part other than a measurement zone (25), and for each measurement zone (25), decorrelating at least one of the pixel data of the images in at least the measurement zone and the time-varying value of a combination of pixel values at at least a number of the image points in the measurement zone (25) from the correction signal. ### Claim 4 (depends on 1) Method according to claim 1, wherein the comparison data is selected from the group consisting of heart rate and respiration rate. ### Claim 5 (depends on 1) Method according to claim 1, wherein the comparison data are based on at least one signal (30;41;55) representative of at least variations in a time-varying value of a combination of pixel values at at least a number of image points of a further selected measurement zone. ### Claim 6 (depends on 5) Method according to claim 5, wherein each further selected measurement zone is one of a number of measurement zones in a grid laid over the images. ### Claim 7 (depends on 5) Method according to claim 5, wherein the determination of whether at least a certain frequency component of the signal (30;41;55) is in phase with a comparison signal to a certain accuracy is only carried out if the signals (30;41;55) obtained for the measurement zone and at least one further measurement zone spaced apart therefrom have spectra with respective local maxima at a frequency common to the measurement zone and the at least one further measurement zone to a certain accuracy. ### Claim 8 (depends on 1) Method according claim 1, wherein the device includes at least one device (8,10-12) for providing a perceptible output, and wherein the method includes controlling the device to provide spatially targeted output differentiated by spatial target in dependence on whether a determination made for a measurement zone (25) corresponding to a target is positive. ### Claim 9 (depends on 8) Method according to claim 8, wherein, for at least one measurement zone (25) corresponding to a target, the perceptible output is adapted in dependence on a value of the frequency of the local maximum. ### Claim 10 (depends on 1) Method according to claim 1, wherein at least one device is made operative in dependence on whether the determination is positive. ### Claim 11 (depends on 10) Method according to claim 10, wherein the device of which the function is controlled is included in a conditional access system (3,13). ### Claim 12 System for detecting the presence of a living being, including: a data processing device (3) having a processor (5) configured to obtain a sequence (19;34;48) of digital images taken at consecutive points in time by a camera, the data processing device configured to: select at least one measurement zone (25) including a plurality of image points; for at least one measurement zone (25), to obtain a signal (30;41;55) representative of at least variations in a time-varying value of a combination of pixel values at at least a number of the image points, and to determine at least one characteristic of the signal (30;41;55) within at least a range of interest of its spectrum relative to comparison data, the determination comprising at least one of: (i) determining whether the signal (30;41;55) has a spectrum with a local maximum at a frequency matching a comparison frequency to a certain accuracy; and (ii) determining whether at least a certain frequency component of the signal (30;41;55) is in phase with a comparison signal to a certain accuracy; and to adapt its output in dependence on whether a determination is positive, wherein the system is unobtrusive to a living being present in a field of view of the camera, and wherein the living being can be in motion. ### Claim 13 (depends on 12) System according to claim 12, wherein the sequence (19;14;48) of digital images is caused to be captured by the camera (2) upon completion of an initialization phase, the initialization phase including: measuring periodic intensity fluctuations in at least parts of images acquired by the camera (2) whilst camera settings are varied, and selecting values of the camera settings at which measured periodic intensity fluctuations in at least a range of frequencies are determined to be minimal. ### Claim 14 (depends on 12) System according to claim 12, including determining a correction signal corresponding to a time-varying value of a combination of pixel values at at least a number of image points in an image part other than a measurement zone (25), and for each measurement one (25), decorrelating at least one of the pixel data of the images in at least the measurement zone and the time-varying value of a combination of pixel values at at least a number of the image points in the measurement zone (25) from the correction signal. ### Claim 15 (depends on 12) System according to claim 12, wherein the comparison data is selected from the group consisting of heart rate and respiration rate. ### Claim 16 (depends on 12) System according to claim 12, wherein the comparison data are based on the at least one signal (30;41;55) representative of at least variations in a time-varying value of a combination of pixel values at at least a number of image points of a further selected measurement zone. ### Claim 17 (depends on 16) System according to claim 16, wherein each further selected measurement zone is one of a number of measurement zones in a grid laid over the images. ### Claim 18 (depends on 16) System according to claim 16, wherein the determination of whether at least a certain frequency component of the signal (30;41;55) is in phase with a comparison signal to a certain accuracy is only carried out if the signals (30;41;55) obtained for the measurement zone and at least one further measurement zone spaced apart therefrom have spectra with respective local maxima at a frequency common to the measurement zone and the at least one further measurement zone to a certain accuracy. ### Claim 19 (depends on 12) System according claim 12, wherein the system includes at least one device (8,10-12) for providing a perceptible output, and wherein the system includes means for controlling the device to provide spatially targeted output differentiated by spatial target in dependence on whether a determination made for a measurement zone (25) corresponding to a target is positive. ### Claim 20 (depends on 19) System according to claim 19, wherein, for at least one measurement zone (25) corresponding to a target, the perceptible output is adapted in dependence on a value of the frequency of the local maximum. ### Claim 21 (depends on 19) System according to claim 19, wherein at least one device is made operative in dependence on whether the determination is positive. ### Claim 22 (depends on 19) System according to claim 19, wherein the device of which the function is controlled is included in a conditional access system (3,13).